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Tendon-Sheaths Lameness Arising from Disease or in Jury of Tendons

LAMENESS ARISING FROM DISEASE OR IN JURY OF TENDONS, TENDON-SHEATHS, AND BURS/R Inflammation of the Bursa of the Biceps Tendon. Bursitis Intertubercularis. This con dition is probably the most frequent cause of shoulder lameness. It occurs in two forms: the acute, which may rapidly subside or may, on the other hand, develop into chronic bursitis.

The causes of inflammation of this bursa may be severe bruising, strain of the tendinous portion of the muscle where it glides over the pulley-like surface of the bicipital groove, from slipping whilst rising or during fast paces; or infection, either local or systemic.

The lesions in acute lameness may be merely inflammatory hyperaemia of the walls of the bursa with increased secretion of synovia. Frequently flocculi are present.

In chronic bursitis, in addition to these lesions, abrasion of the cartilage of the bicipital groove occurs and exostoses may develop on the head of the humerus. Occasionally the biceps muscle itself becomes ossified, chiefly through deposition of lime salts in the fibrous bands which traverse its length. Cases have been reported in which the biceps muscle was ossified and united throughout to exostoses on the shaft of the humerus.

Symptoms. In acute cases the animal can only raise the foot from the ground with diffi culty, and this action is accompanied by mani festation of pain. There is always marked lameness when an attempt is made to advance the leg, and whilst in motion the horse carries the affected shoulder behind the level of the other and"steps short"on the lame leg. No weight is placed upon the affected member.

In backing, lameness is not usually so marked.

A characteristic of shoulder lameness is that weight is carried longer on the sound limb, which is then jerked forward quickly with a sort of"hopping"motion.

Whilst at rest the knee is usually flexed and the shoulder-joint extended somewhat, the foot being carried behind its normal level and resting on the toe. This is seen only in severe cases. Mild inflammation may not be accompanied by any noticeable symptoms whilst the animal is at rest. Sometimes the foot is held in front of the other as in"pointing,"but the foot is placed squarely upon the ground and does not rest upon the toe.

Local indications of bursitis may be absent, or there may be slight swelling of the front of the shoulder, due to distension of the bursa, and when pressure is brought to bear upon it the horse may exhibit pain. Most horses will flinch, however, when the shoulder region is pinched or pressed upon with the fingers, and error in diagnosis is therefore possible. A sudden backward pull upon the limb causes great pain. In chronic cases lameness is seldom so intense, and apart from shortening of the forward stride little defect of action may be noticeable, and the animal may work for months without showing marked lameness except when travelling uphill. Whilst at rest the limb is usually carried a little behind its fellow, but the foot usually appears capable of bearing some weight. Local examination usually reveals exostosis on the front of the head of the humerus, and in severe cases the biceps tendon itself may become bony.

Sometimes the condition is bilateral, and the symptoms then bear some resemblance to laminitis. The gait is restricted in front to short, hesitating steps, whilst the hind legs are carried under the body with the object of reliev ing the shoulders of the weight of the body.

Treatment. —In acute bursitis the hose- pipe probably presents the most useful remedy, and cold irrigations are certainly indicated during the inflammatory stage. When lameness dimin ishes somewhat, counter-irritation is beneficial, and blistering is often sufficient. Rest in a level field or loose-box is essential.

In chronic cases little can be done. Repeated blistering and the actual cautery may be tried, though as a rule treatment is useless, but the course of the disease is not so rapid as might be expected, and frequently the horse remains more or less workable for some considerable time. Acute bursitis should recover in from six to eight weeks, or it may become chronic.

Old-standing cases with moderate lameness are often benefited by shoeing with thickened heels.

Strain of the Infraspinatus Tendon with Bursitis. The outer division of the infraspinatus tendon plays over a smooth surface on the con vexity of the external tuberosity of the humerus before being inserted into a rough oval mark between the summit and deltoid tubercle. Between the tendon and the convexity a synovial bursa is interposed.

As in bursitis intertubercularis, either direct violence in the form of bruising from kicks, falls or collisions, or strain of the tendon itself, may produce inflammatory changes in the walls of the bursa.

The infraspinatus is an abductor of the humerus, and according to some observers strain of the tendon is commonest in horses with narrow chests and closely-placed fore legs used for fast work. Under such circumstances the increased abduction of the shoulder neces sitated by this conformation is likely to cause undue strain of the infraspinatus tendon.

Symptom8. Lameness is most noticeable when weight is placed upon the foot and when the animal is moved in circles. In mild or sub acute cases lameness may only be evident upon starting off and when turning, particularly in the same direction as the lame leg.

Swelling is not always present or visible, but there is usually atrophy of the infraspinatus resulting from lack of use of this muscle. Pal pation of the diseased bursa usually causes pain.

Prognosis. — The lameness often recovers under proper treatment and has not the same tendency to become chronic as has that caused by bursitis intertubercularis. About six to eight weeks may be required to effect recovery.

Treatment. Cold applications followed by a blister and rest in a level field are usually all that is required. If this treatment fail, the actual cautery should be employed.

Inflammation of the Subcutaneous Bursa of the Elbow. Capped Elbow. This condition in the horse results from bruising of the sub cutaneous bursa overlying the olecranon process of the ulna.

The cause is almost invariably bruising of the bursa and subcutaneous tissues as the result of pressure from the inside heel of the shoe or from the foot whilst the animal is lying. Occasionally, however, lack of bedding or a habit of scraping back the straw, or rough, uneven flooring may be responsible. In the latter case the resulting condition is usually somewhat different from that which is generally recognized as"capped elbow,"and will be described later.

The particular manner in which the horse lies, or undue length of the inner branch of the shoe, may be predisposing factors. A somewhat uncommon cause may exist in hacks, hunters and polo ponies, when the toe of the rider's foot may cause the injury.

Symptoms. Capped elbow may assume various appearances according to the nature and extent of the injury and its duration.

In the early stages there may be little more than an cedematous, almost painless swelling involving the point of the elbow. In other cases we may observe a very diffuse, hot and painful enlargement extending for a con siderable distance above and below the elbow, and the point of the elbow itself may be dis guised by the extent of the swelling. Usually the cedematous condition becomes concentrated after a few days around the site of the bursa, so that a swelling may remain as large as a cocoa nut. Lameness is always severe in this type of injury, at least during the early stages.

This excessive amount of swelling with accom panying heat and pain usually points to suppura tion taking place in the bursa itself. Slight cedematous swelling at the point of the elbow generally indicates distension of the bursa, not necessarily accompanied by infection. The enlargement may suppurate and burst, dis charging a considerable amount of thin, bloody purulent matter, or it may assume the cystic form and become chronic, appearing as a well defined enlargement without heat or pain, and containing a thin serous or sero-purulent fluid within one or several cavities.

The most common chronic type of capped elbow is the indurated form, which may be and usually is quite small, or it may be as large as a child's head. The enlargement is mainly due to plastic infiltration, followed by the formation of fresh connective tissue, though the exciting cause is in almost every case inflammation of the bursa (parabursitis and bursitis).

Sometimes as 'a result of lying without sufficient bedding, upon stones, a chronic sup purating condition results. Just below the point of the elbow a small fistula develops, usually communicating with the olecranon bursa. The condition is most often bilateral.

A constant discharge of frothy, sticky pus issues from these wounds and soils the back of the limb as far as the knee or foot. In the early stages the discharge may be oily in character, but in a short time becomes purulent.

Chronic indurated capped elbow has always a tendency to again become acute unless the exciting cause, i.e. bruising, be removed. As horses cannot be induced to lie in an attitude different from that to which they have been accustomed, this is not an easy matter and necessitates the use of mechanical appliances, which will be discussed later.

Lameness is not usually a symptom of chronic indurated capped elbow, though it almost con-. scantly accompanies the acute form.

Treatment. This may be either preventive or curative. When the inner heel of the shoe is the cause of the trouble, a threli-quarter shoe will be found to be beneficial, especially in the very early stages of the condition. Chronic in duration in ay thus be avoided and relieved of pressure and further bruising. Absorption of the exudate may take place and the swelling subside.

There are many appliances on the market for the prevention of capped elbow, all of which aim at preventing the heel of the foot from coming into contact with the point of the elbow. The simplest and perhaps the most efficient of these appliances consists of a"stuffed"leather ring which is strapped around the coronet and projects sufficiently to cause a space to be left between the elbow and heel whilst the horse is lying. It is sometimes preferable to adjust the pad above the fetlock.

As an emergency measure a thick straw band wound round the cannon at night-time answers very well when no pad. is at hand. Plenty of bedding is also advisable, and when the horse is tied in a stall sufficient length of halter rein should be allowed to permit of his lying in comfort. Some horse-keepers strap a pad or cushion below the sternum at night in order to raise the level of the elbow when lying.

Curative treatment varies according to

the extent and duration of the injury.

Painful cedematous swelling may be treated by cold fomentations followed by the applica tion of astringent antiseptic lotions. Lead and alum, white lotion, lead and arnica, or strong solutions of magnesium sulphate may be em ployed. This treatment, together with removal of the cause, may bring about recovery.

When no improvement follows after several days, the parts may be wrapped in a warm kaolin poultice and covered by cotton-wool and some waterproof material. This may be left in position for at least twelve hours without removal. The powdered kaolin should be well rubbed down in a mortar with a little salt and treacle, warm water being subsequently added until a smooth paste is obtained. An anti septic may be added if desired. After two or three of these poultices have been applied it will be found in most cases that a considerable reduction has occurred in the size of the swelling. The parts should then be lightly blistered with biniodide of mercury ointment applied every week or ten days.

On the other hand, should infection have occurred the fluid contents will be evident upon palpation and surgical interference becomes necessary. We are of opinion that large swell ings containing a considerable quantity of serum or blood should always be opened whether infected or not. This statement may possibly meet with opposition from many veterinarians who might consider it an unwise proceeding to expose a closed sterile cavity to certain infection by incision, but the fact remains that such an extravasation area always becomes considerably organized and results in chronic induration with the production of a large, objectionable swelling which is liable at any time to become bruised by the foot or by the ground whilst the horse is lying and to again become the seat of an acute inflammation. Puncture by means of a trochar may result in the withdrawal of a large quantity of serous fluid, but, even if asepsis be maintained, the operation is invariably un successful, as in the course of a few hours the cavity will be just as distended as before. We have attempted to avoid this by blistering im mediately after puncture, but without success.

Free incision from the lowest part of the swelling, in an upward direction, and sub sequent injection of Villate's solution or of iodine solution after free curettage of the walls of the cavity is to be recommended.

Subsequently daily exercise in a paddock assists drainage and helps in reducing the swelling.

Rainey"found that

capped elbow amongst army horses was due to the bedding being placed too far back, with the object of prevent ing the horses from eating it. His treatment of the condition is worthy of mention.

After clipping off the hair from the swelling and painting with tinct. iodi he secured local anaesthesia by the use of novocaine. A Syme's abscess knife, guarded by the fingers from enter ing too deeply, was inserted at the highest point of the swelling and carried by one powerful vertical incision right through to the lowest point. After escape of the contents the flaps were held apart and all loose shreds and necrotic tissue were dis sected away. The cavity was washed out thoroughly, plugged with wool soaked in tinct. iodi, and sutured loosely. The stitches and plug were removed in twenty-four hours and the hose-pipe turned on the wound for half an hour, after which the wound was again plugged with tinct. iodi on wool as before. This treat ment was continued twice daily, the horses being kept on pillar reins.

Twenty horses with capped elbow in all stages were thus treated successfully, and were all discharged to duty within a month, healing being practically complete and little or no trace of the previous enlargement being visible.

The treatment of chronic indurated capped elbow is usually surgical, although good results have been reported from the injection of various thiosinamine preparations.

Good results often follow puncture with a scalpel to liberate the fluid contents, which may be of considerable amount in even very solid looking enlargements. The cavity should then be plugged with wool or tow smeared with ung.

hydrarg. biniodid. 1: 8 or ung. iodi 1: 8. This dressing should be changed daily. Pendulous enlargements may be removed by elastic ligature or ecraseur, whilst some operators recommend the clam and actual cautery.

To avoid slipping of the ligature, a couple of thin aluminium skewers may be inserted at right angles to each other above the swelling and their pointed ends coiled round in several turns. The ligature of elastic or whipcord is then affixed above these. Healing, after slough ing of the tumour, usually occupies three weeks and recovery is more rapid after surgical enucleation of the fibrous mass.

Care must be taken of the point of the ole cranon whilst operating, and it is advisable thoroughly to curette the cavity to remove any secretory lining which may have been left behind. The wound should then be rendered as nearly sterile as possible by swabbing with tinct. iodi and should then be sutured. If the tumour was originally of large size the excessive skin should be partly removed and after suturing the edges the remainder should be kept in contact by means of deeply placed sutures so as to avoid the presence of a cavity which might retain the discharges. The stitches and external skin should be frequently swabbed with iodine solution.

Bent Knee. - Whilst usually arising in aged or hard-worked horses from contraction of the flexor muscles of the knee or their tendons,"bent knee"may be due to various other causes. Inflammation of the carpal sheath, con tracted tendons, arthritis of the knee-joint, sore shins and acute osteo-periostitis of the meta carpal region may give rise to the condition, whilst in foals and two-year-olds contraction of the flexor perforans and perforatus muscles may cause knuckling at the knee.

The condition may thus be acute or chronic, according to the cause. The chronic type is by far the more common and can only be relieved by tenotomy, i.e. section of the flexor tendons of the knee, though section of the perforans tendon may be necessary when the seat of the trouble is in that region. The external tendon should be first divided, and if this does not result in straightening of the knee, the middle flexor should be divided also.

Knuckling due to other causes must be treated accordingly. Young horses affected with splints should be point-fired, blistered, and turned out to graze where they will get exercise and so prevent the condition from becoming chronic, owing to contraction of the tendons of the flexors of the knee.

Distension of in the Carpal Region.A dropsical condition may occur in the sheath of either the extensor tendons as they glide over the front of the knee or of the flexor tendons during their passage through the carpal arch."Capped"or"bumped knee"may be due to subcutaneous effusion or it may involve the tendon-sheaths of the extensor pedis or extensor metacarpi magnus, usually the latter. The sheath itself may be distended with serum, or as sometimes happens, especially in long-standing cases, the enlargement may be caused by fibrous thickening of the tendon sheath itself. Suppuration may occur, but more frequently the cavity contains serous fluid, sometimes containing a very large number of whitish bodies, in shape much resembling cucumber seeds, the so-called Corpora oryzoidea.

The flexor sheath at the back of the knee is supported by firm fibrous coats in the neighbour hood of the joint itself, but above and below this the sheath is not protected in this manner and is therefore liable to become distended, producing the so-called"knee-gall."This may occur on either the inner or outer side of the limb, more commonly on the inner.

The sheath of the extensor suffraginis is occasionally involved. The swelling is con fined in most cases to the outside of the knee and lower end of the radius. Distension of the sheath of the oblique extensor is characterized by the presence of a sausage-shaped swelling passing obliquely over the front of the knee from the middle of the lower end of the radius as far as the head of the inner small metacarpal bone.

Causes. Traumatic injury may produce dis tension of the extensor tendon-sheaths, as in"capped knee"by repeated bruising whilst lying or by striking the knee against a wall or manger. Williams stated that the condition might be caused at times by the entrance of thorns whilst hunting and jumping thorn hedges, and that these thorns might remain in for years without causing any apparent inconvenience to the animal, beyond some swelling.

Undoubtedly the most common cause of dis tension of the tendon-sheaths is overwork or lack of rest, whilst strain of the tendon itself may be responsible and attended by filling of the cavity with blood or serum.

It is generally agreed that hereditary in fluences play some part in the production of these enlargements, though what is actually transmitted is not clearly understood unless it be some defect of the synovial secreting mem brane.

Symptoms. During the acute inflammatory stage, distensions of the extensor-sheaths may cause lameness. There is swelling along the course of the affected tendon, heat, pain upon pressure and constant enlargement both whilst the foot is raised from the ground and when weight is placed upon it. Moller points out that bursal enlargements diminish when the limb is flexed or relieved of weight. The swelling is always vertical except in the case of the oblique extensor, whilst articular enlarge ments are usually transverse in direction.

Chronic distension of the extensor tendons seldom produces lameness, and apart from dis figurement no actual inconvenience is caused to the animal. Distension of the carpal sheath of the flexor tendons is a more serious condition. The carpo-metacarpal sheath, extending from about two inches above the carpus to near the middle of the cannon, lines the carpal arch and part of the metacarpal aponeurosis, is reflected on both tendons in the carpal arch and below on the perforans, posterior surface of the sub carpal ligament and anterior surface of the perforatus tendon. From an inch or two below the carpal arch to the upper margin of the sesamoid sheath the perforatus has no synovial on its posterior surface, and the anterior surface of this portion of the tendon is separated by loose connective tissue from the parietal synovial of the perforans.

Strain of the perforatus in the region of the knee is complicated by synovitis of the carpal sheath, which considerably aggravates the lame ness and delays recovery.

Inflammation and distension of the flexor synovial sheaths may also accompany or follow various diseases, such as influenza, strangles, purpura, pneumonia, glanders, nasal catarrh, laminitis, lymphangitis, castration, wounds, etc. In foals this condition may be primary or congenital, contracted from the dam, and complicated by myositis of the flexors.

Toxic inflammation of tendon is denied by some who admit the occurrence of toxic synovitis of the flexor sheaths. Both forms are affirmed by others who maintain that the synovitis pre cedes the tendinitis. Symptoms and effects are variable; in foals bent knees, knuckling, or sinking of the fetlocks, oedematous tendons, swollen fetlocks and pasterns, knees, or hocks; unthrifty condition.

In older horses there is diffused painful swelling—no part thicker than another—of flexor tendons of one or both fore or hind limbs; synovitis of sesamoid, carpal, or tarsal sheath; lameness, knuckling, constantly lying down, sometimes marked sweating, and pro gressive emaciation.

Prognosis is generally favourahle in foals; doubtful in older animals, in which rapid recovery may follow indifferent treatment, or the case, in spite of every attention, may linger for months, with thickened tendons, lameness, and chronic knuckling. Prevention has not been tried.

Carpal tenosynovitis arising from strain is almost constantly associated with thickening of the tendon as well. The symptoms will be described under"Injuries to the Flexor Tendons." Treatment of distensions of the extensor tendons which pass over the front of the knee must depend upon the severity or absence of lameness, the nature of the work, and the value of the animal. In horses used for exhibition there may be a strong desire on the part of the owner to remove what may be actually only an eyesore. In others, in which the working capability is not diminished, interference is seldom called for.

When acute inflammation exists, cold fomenta tions, preferably applied by means of the hose pipe, followed by the application of a thick layer of wool and a flannel bandage, may be sufficient, or an astringent lotion may be employed in addition. The cotton-wool pad may be soaked in a lotion containing plumbi acetas and alum, whilst some veterinarians favour the employ ment of a strong solution of magnesium sulphate. Hand rubbing or the use of stimulating lini ments is not advisable, as an increase in the exudation may be produced by mechanical irritation.

When acute symptoms have subsided a bin iodide of mercury blister is useful, as it tends to reduce the enlargement and by thickening the skin produces a local mechanical pressure assists in absorption of the exudate.

In place of biniodide of mercury ointment we may employ a lotion containing 5 grains to the ounce of water, the solution being effected by the aid of potass. iodid., or a lotion may be used containing iodine 5 grains and hydrarg. biniodid. 5 grains to the ounce of water together with sufficient iodide of potash to produce solution. These applications should be painted over and around the affected tendon sheath daily until soreness is produced, when their use should be discontinued for a few days.

Surgical interference has found many sup porters, principally on the Continent. It must be borne in mind that communication some times exists between the extensor sheaths and the joint capsule, and hence asepsis is indis pensable and not by any means easy to secure at the time of operation or to maintain sub sequently.

Withdrawal of the contents with the aspirator, followed by injection and subsequent removal of a 1 per cent iodine solution, may prove beneficial, especially if repeated on several occasions, and is not likely to be followed by any ill-effects if properly performed. Puncture of the swelling by means of a fine needle-pointed iron at red-heat, followed by squeezing out of the contents and the immediate application of a blister, may answer the same purpose, but simple puncture is seldom successful as the secreting membrane is not destroyed and the cavity refills almost at once. It is stated that injection of iodine solution at first produces a crop of granulations, and that subsequently the normal action of the secreting membrane is restored. The same is said to follow drainage produced by inserting a perforated rubber tube through the length of the swelling.

Line-firing is only of service when lameness persists, as it produces a blemish equal to that caused by the original swelling.

Very frequently in old-standing cases the contents are no longer fluid but fibrinous, and difficulty is experienced in withdrawing the con tents through a trochar. In this case if removal of the enlargement be essential, nothing remains but radical operation. The skin must first be rendered as nearly aseptic as possible. An elliptical piece is then removed in the direction of the long axis of the swelling and all fibrinous clots removed. Careful curettage of the walls of the cavity should then be performed and the latter plugged with cotton-wool soaked in weak iodine solution until all haemorrhage has ceased.

This is an important point, as otherwise the sheath becomes refilled with blood-clots. The edges must then be closely sutured with silk, but the needle should merely penetrate the skin and should not be carried through the walls of the tendon sheath or secondary infection will almost certainly occur.

The seat of operation should next be painted with iodoform collodion and bandaged over wool. The horse must be subsequently kept as still as possible, preferably in a sling, and if thought advisable the movements of the knee may be restricted by means of a splint.

The bandage and dressing may be left in position for ten days, provided asepsis has been maintained.

The treatment of toxic tenosynovitis may be local and systemic, the latter is of chief import ance. For the foal, good hygiene, intensive diet ing, tonics, and antiseptics; locally, plaster or starch bandages to support, or flannel bandages to protect the fetlocks. For older patients, potassium iodide, sodium salicylate, salol, quinine, antistreptococcic serum may be tried; locally, at first, warm or cold applications, com presses, fomentations; later iodine ointment, blisters, oleate of mercury, and, if required, cauterization. B. H. S.

Injuries to the Flexor Tendons and Suspensory Ligament It is desirable briefly to recall the arrange ment and relations of the structures exposed to injury.

Fore Limb. The flexor perforans muscle, three times larger than the perforatus, arises from the humerus, radius, and ulna, and extends to near the knee where its tendon begins. The tendon passes through the carpal arch to the middle of the cannon, where it is joined by the subcarpal ligament, then downwards to the fetlock, where it passes through the perforatus ring and over the sesamoid pulley. Descending behind the pastern, under the bifid insertion of the perforatus and over the glenoid prominence and navicular bone, it is inserted on the semi lunar crest of the os pedis. Slightly compressed at the knee, it is rounder at the cannon, consider ably expanded and flattened at the fetlock, narrowed though still flat behind the suffraginis, at the os to which it is loosely attached, it again expands and rapidly attains its greatest breadth at its insertion. In volume it varies little from its origin to the point of junction with the subcarpal ligament, and below this the increase is hardly noticeable owing to the gradual attenuation of the reinforcing band. At the fetlock the tendon is thicker, and its anterior surface, moulded on the sesamoid pulley, shows some of the characters of fibro cartilage. Another increase in thickness and firmness occurs at the os coronae. It appears to be weakest at its terminal expansion, which, however, is well supported by the posterior digital ligament.

The subcarpal or"check"ligament, a direct continuation of the posterior common ligament of the knee, is united at its origin to the anterior fibrous wall of the carpal arch and the suspensory ligament. Descending, it closely embraces the anterior surface of the perforans, which it appears to join at the middle of the cannon. In many instances their fusion is very gradually effected, as some indication of the parts of tendon and ligament can be traced to near the fetlock. The subcarpal ligament is the strongest portion of the suspensory apparatus of the fetlock.

The perforatus or superficial flexor muscle, arising with a portion of the perforans from the humerus, extends to near the knee where it is succeeded by tendon. In close contact throughout with the perforans, the tendo perforatus passes through the carpal arch to near the fetlock, where it forms a sheath-like ring for the perforans, then descending and becoming somewhat broader it terminates by a bifid insertion on the os comm. Before enter ing the carpal arch the perforatus is joined by the radial ligament.

The radial ligament arises from the inner border of the posterior surface of the lower extremity of the radius and extends obliquely downward and outward to join the perforatus tendon. It is a short, rather lax fibrous band, between two and three inches long, about an inch broad, and less than half an inch thick. In Germany and France, cases of lameness have been attributed to strain of this ligament.

The suspensory ligament, arising from the lower row of carpal bones and the head of the cannon, descends between the subcarpal liga ment and metacarpus to near the"buttons,"where it bifurcates. Each branch is implanted on the excentric surface of the corresponding sesamoid, and a portion of each band is con tinued downward and forward to join the extensor pedis tendon. From its origin to the point of bifurcation the suspensory is flattened and closely applied to the cannon, its branches to the sesamoids are rounded, and the extensor bands are flat. It has a covering of connective tissue which attaches it to the cannon and flexor aponeurosis. In structure it differs from the tendons by containing fasciculi of striped muscle and some fat.

Hind Limb—Flexor Tendons. Apart from their points of origin and a few other differences, the more important features are: the perforans in the tarsal arch is not accompanied by the perfo ratus; at the upper metatarsal region it is joined by the tendon of the accessory flexor muscle, and near the middle of the shank by the subtarsal ligament, which though longer is less thick or strong than the subcarpal ligament. The perforatus has a very short muscular portion, and its tendon, beginning just below the upper third of the tibia, after a winding course, reaches the point of the hock, where it forms a cap for the summit of the os calcis. Below the hock the perforatus descends the shank, as in the fore limb, to the os coronae.

Tendon is made up of groups of parallel white fibrils, interspersed with flattened nucleated con nective tissue cells, arranged in rows running in the direction of the tendon fibres. Between the bundles are interfascicular spaces, and primary and secondary connective tissue septa, continuous with the peritendinous covering.

The nerves (few and non-medullated), blood vessels, and lymphatics ramify in the septa. The subcarpal and subtarsal ligaments have thicker interfascicular septa and are more vascular than the tendons.

Peritendineurn. Each tendon has its own covering of connective tissue. This is com posed of several laminae, more or less united, closely investing the tendon, continuous in wardly with the interfascicular septa, and connected outwardly, according to the part examined, with the visceral layer of the flexor synovial sheath, the common aponeurosis, or the adjoining tendon or ligament. Between its laminae the vessels and nerves break up to penetrate the interfascicular septa of the tendon.

Aponeurosis. The metacarpo-phalangean or common aponeurosis furnishes a subcutaneous covering to the flexor tendons and subcarpal ligament, and separates these from the sus pensory. It consists of two principal layers of fibrous tissue, united to each other and to the tendons or parietal synovial sheath by areolar tissue and continuous with the posterior wall of the carpal arch and fascia of the forearm. It forms a strong fibrous brace for the flexor Fie. 163. Seetion of the flexor tendons of a four-year-old horse, at the point of union of the subearpal ligament and perforans.

A, perforatus; B, perforans; C, subcarpal hg. (After Pader.) tendons at the sesamoids and pastern, and supports and protects the vessels and nerves. In the hind limb the metatarso - phalangean aponeurosis is similarly arranged.

Synovial Sheaths. Facilitate movement of the tendons, and consist of two parts continuous with each other — a parietal, lining the apo neurosis or other supporting tissue, and a visceral, investing the proper covering of the tendon. The opposed surfaces are lined with endothelium. The carpo-metacarpal sheath and the great sesamoid sheath are described on pp. 706 and 721.

Strain. Strain, partial rupture of tendon or tendinitis, varies in gravity with the degree of injury, the position of the strain, and the cord affected. Strain may be slight and limited to a few axial or peripheral fibres (tendinitis), or severe, and involve a considerable portion of the thickness of the tendon, including its con nective tissue - covering (paratendinitis). In strain affecting few or many fibres the ruptures may occur at one level (short strain), or owing to subsequent tearing or secondary ruptures at different levels, the laceration may represent a sloping breach of the tendon (long strain). In most cases there is a centre of limited rupture, but owing to consecutive inflammatory changes the distension extends above and below the seat of injury. In this way, amongst others, the diffused thickening of the subcarpal ligament and the elongation of the primary distension of"bowed"perforatus are produced.

Position of Strain. The perforans, though far less frequently affected than is generally supposed, may be strained just under the knee, at its junction with the subcarpal ligament at the sesamoids, behind the pastern or in the"heel pan,"where it is very difficult to dis tinguish distension of this tendon from rupture of the digital aponeurosis or bursitis of the synovial sheath. The subcarpal ligament may be strained close to its fusion with the perforans, near its origin below the knee, or towards the fetlock at its real termination. The strain may be short or limited to an inch or two of the ligament, but as there is a constant tendency to extension of the inflammation, most often the distension is diffused.

The perforatus may be strained at the knee, at the middle of the cannon, or at the fetlock. Occasionally strain occurs at other points, as within the carpal arch and at the bifurcation of the tendon behind the pastern. Strain of the radial ligament as a primary injury must be very rare, though acute bursitis of the carpal sheath, caused by bruising, sometimes extends to this ligament.

Strain of the suspensory usually occurs im mediately above its bifurcation or affects the inner branch. In dilaceration or upward splitting of the suspensory the apparent strain may extend to the upper third of the ligament.

The relative frequency of strain at these sites cannot be positively stated, because cases are seldom seen early enough to permit of accurate diagnosis. But perhaps the commonest strain of the perforatus is represented by"bowed tendon"at the middle of the cannon; that of the perforans at the fetlock, and that of the subcarpal ligament near its junction with the perforans, except in cart horses, in which the lesion is oftenest near the origin of the ligament.

Regarding the comparative frequency of per forans, perforatus, subcarpal, and suspensory strain there is hardly more justification for confident assertion. However, one may say that in cart horses the subcarpal ligament is more often strained than the perforans, that by extension of inflammation the perforatus is often implicated, and that strain of the sus pensory is very seldom seen. In saddle horses, racehorses, chasers, hunters, and polo ponies, strain of the perforatus or of the suspensory is more common than strain of the perforans. Anterior strains are much more frequent than posterior strains.

Statistics and published cases of flexor strain should not be accepted without caution. Re peated examination of the leg is required to distinguish the tendon strained, and in many cases some doubt remains. Poy, analysing 230 cases of anterior strain in horses engaged at fast work, gives 116 suspensory alone, 17 suspensory and one tendon, 34 perforatus, 30 both flexors, 16 subcarpal ligament, 10 subcarpal and one tendon, and 7 perforans. Barrier found the suspensory affected five times in 11 cases, and Jacoulet thirteen times in 18 cases of strain in saddle horses; and in six months at Saumur, Joly had 75 cases in horses particularly exposed to strain by attenuation of shock: 25 per foratus, 17 suspensory, 17 affecting the tissues connecting the perforatus and subcarpal, 1 per forans, and 8 affecting the tendons without possible distinction. Lesbre, from observa tions made in the dissecting-room, considers that the subcarpal ligament and perforans are more frequently strained than the suspensory. Other observers have found the suspensory affected twenty-four, fifty, and fifty-four times in 100 cases of strain, and Pader states that probably many cases of apparent distension of the suspensory may be due to Filaria reticulata, as in 37 cases of parasitic invasion of this ligament, 13 presented enlargements identical with the lesions of chronic strain. In nine years, according to Frohner, 36,230 horses of the Prussian Army were treated for inflammation of the flexors and tendon-sheaths, and of this number 70 per cent were affected in both flexors of one limb, and 20 per cent in the sus pensory. The right fore leg was affected in 43 per cent, and the left in 36 per cent of the cases. Later German statistics give, for one year, 2695 cases: 1090 both flexors, 495 sus pensory alone, 401 perforans alone, 286 per foratus alone, 120 both flexors and suspensory, 49 subcarpal ligament, 1 radial ligament, and 45 synovitis or rheumatic tendinitis. In the French Army the admissions for strained tendons and fetlocks were 1080 in 1891, and 3923 in 1897. In the British Army, with an effective home strength of 21,000 horses in 1907, the admissions for strained tendons were 634, and for strained ligaments 834. Unfortunately the distribution of these strains is not given in the report from which these figures were obtained, but the small number of cases is both remark able and gratifying.

Causes. Predisposing or contributing and exciting causes are recognized, but as many of these appear to be interdependent they will be placed together. Defective conformation is represented by long, upright, or too oblique pasterns, buck knees, crooked legs, and tied-in tendons. Bent knees, especially when con genital, should be excepted, as they appear to save the tendons, and in this belief some owners and trainers prefer horses that lean a little at the knees. Tendons, though thick and appar ently strong, may be weak, defective in quality, of unequal density, less resistant, and more liable to strain; these defects being due to heredity, breeding, rearing, or dieting. Other causes are premature work or training before complete growth or consolidation of the tendons and ligaments; forced training or pushing the preparation of the young horse; nervous excita bility in thoroughbred and some other horses, by inducing more energetic efforts; fast work, especially racing, chasing, hunting, and trotting (perforatus and suspensory strains); muscular fatigue towards the finish of a fast-run race or in galloping too far, and weak flabby muscles, by relaxing the flexors and too suddenly throw ing the support of the fetlock on the tendons; heavy draught work, starting or backing a load, holding back going down hill, and shunting (subcarpal or perforans strain); antecedent disease, adhesions, with or without shortening, worn tendons, chronic disease of tendon, apo neurosis, or synovial sheath; hard ground, by increasing the flexion of the pastern and the tension of suspensory and perforatus; heavy holding ground by detaining the foot, impeding movement and increasing effort; ground with a soft or movable surface-layer, as grass after rain, and wood or asphalt when wet or greasy, by causing slipping; ringbone and enlargements of the pastern by hindering or preventing move ment of the joints and consequent relaxation of the tendons (perforans strain); long toes and low heels and shoeing with tips predispose to strain of perforans and perforatus. Slipping in the stable or on the road, a false step, and in a tired horse a sudden acceleration of speed may cause strain.

In forming an estimate of the merits of these causes, attention should be given to the action of the fetlock and pastern. The fetlock, with its angle open in front to about 150°, is sus tained by the suspensory and supported by the flexor tendons. The suspensory yields a little when the fetlock sinks and regains its former length when the fetlock rises. In movement, the tension of the suspensory is in proportion to the degree of dorsal flexion of the fetlock, and if it is elastic the property of stretching is due to the muscular fasciculi incorporated with its fibrous tissue. Immediate post-mortem examination of the suspensory reveals no sign of special elasticity, and in the thoroughbred during movement it appears to be rather thicker when tense than when relaxed. Pader holds that the suspensory is not more elastic than the tendons, and Lesbre suggests that the lengthening or yielding of this ligament is more apparent than real because of its bifurcation and the position of its attachments to the pastern. Implanted on the free or outer side of the sesamoids, it acts like a cord suspending the pulley by its axis, and when the fetlock descends the sesamoid mass passes between the branches of the ligament. However this may be, the suspensory acts by a direct pull on the sesarnoids, while the flexor tendons furnish a movable support to the fetlock, and together tendons and suspensory may be regarded as a single power acting_ at the sesamoids on the lever of the pastern to oppose the descent of the fetlock and closure of its angle in front. In the standing position the weight transmitted through the cannon falls on the fetlock, where it meets the inclined articular surface of the pastern and is resolved into two parts, one perpen dicular to the inclined surface, the other parallel to it. The perpendicular weight exerts its pressure on the pastern bones, which neutralize it by their resistance, while the other part, which abuts behind on the sesamoids, tends to force the fetlock downwards by inducing oscilla tion of the pastern lever with consecutive clos ing of the metacarpo-phalangean angle. This tendency is overcome by the tension of the suspensory apparatus, which keeps the fetlock in position and preserves its normal angle. In locomotion, when the foot comes to the ground, the pressure supported by the fetlock is repre sented by the weight of the body plus the force of inertia resulting from the acquired speed. The more rapid the pace the greater the pressure. And while the foot is in contact with the ground the fetlock, at first, is a centre of attenuation of shock and afterwards a centre of impulsion. Its mechanism was investigated in 1891 by Barrier and Siedamgrotzky. Working inde pendently, with the assistance of instantaneous photography, they arrived at very similar con clusions, which as regards the causation of strain may be shortly stated: When the foot is coming to the ground, the oblique cannon forms with the pastern a straight line (Fig. 164, 2). When the foot is in support the cannon becomes vertical, while the pastern approaches more or less the horizontal. In virtue of the marked dorsal flexion of the fetlock, the pastern or phalangean lever oscillates in two different directions: forwards and upwards on the cannon and downwards on the os pedis and navicular. These two movements of oscilla tion are absolutely simultaneous, and they pro duce at once closing of the angle of the fetlock and flexion of the coffin-joint (Fig. 164, 3). But the effect of this closing of angles is different on each flexor tendon. The perforans, repre senting a cord extending from the head of the cannon (origin of subcarpal ligament) to the os pedis, is relaxed, the inflexion of the pastern having shortened the distance between its two points of insertion. The perforatus, extending from the radial ligament to the base of the pastern, is made tense, in consequence of the separation of its points of attachment, and for the same reason it more closely braces the fet lock. Towards the middle of this stage the suspensory reaches its maximum of tension and is most exposed to rupture.

From this moment of the support, the angle of the fetlock effects a sort of forward oscillation, the pastern straightens and the flexion of the coffin-joint progressively diminishes, whilst the cannon is inclined forwards (Fig. 164, 4). This 1 2 3 4 oscillation of the fetlock and the simultaneous straightening of the pastern have the effect in a fast pace—as a striding gallop—of effacing the angle which was formed at the hoof, of producing a little greater closing of the meta carpo-phalangean angle. Under the influence of these two causes the tendons are immediately stretched and quickly reach the limit of their extension. The more extensive the oscillation of the angle of the fetlock on the articulation of the foot the greater the tension of the sub carpal ligament, so that at this instant the least supplementary effort may cause a rupture.

Inferentially these observations may be sum marized: (a) strain of the suspensory is pro duced by excessive tension (paratonia) of the ligament at the moment of greatest dorsal flexion of the fetlock, when by inflexion of the coffin-joint the semilunar crest is brought nearer the sesamoid pulley and the perforans is relaxed (Fig. 1(34, 3). (b) The perforatus may be strained in the same way as the suspensory, with which it shares the charge of supporting the fetlock when the foot comes to the ground. (c) Strain of the subcarpal ligament or perforans is pro duced by excessive tension (paratonia) of the tendon at the moment of hyper-extension of the pastern during impulsion in fast work or in forced draught (Fig. 164, 4).

In the first stage of the support (Fig. 164, 3) some hesitation arises regarding the action of the perforans and subcarpal and their escape from strain. The very limited relaxation of the perforans tendon at the coffin - joint can hardly be sufficient to permit the angle of the fetlock to close to the extent seen in racing, when the ergot almost touches the ground. The tendon is inextensible, and its apparent elongation when the fetlock descends should be referred to the muscle. The subcarpal liga ment is not constantly tense, and it is reasonable to suppose that the perforans muscle is stretched before this ligament is called upon to share the pull on the tendon. In racing and similar fast paces muscles sooner or later become fatigued, and as they are not continuously contracted, when strain of the subcarpal does happen at this stage, most likely the injury occurs during relaxation of the muscle, when the ligament, unassisted by muscular contraction, is in extreme tension.

Regarding strain of the perforatus the opera tion of the cause is not clear. At the fetlock this tendon moves freely on the perforans, and, according to Joly, with the advantage of having watched the action of the naked flexors in a living horse, the perforatus begins to move and comes to rest a little sooner than the per forans, which appears to continue the move ment. The perforatus muscle is small, pre sumably weak and easily stretched, and the radial or check ligament is lax enough to allow for elongation under tension. No doubt partial rupture of this tendon sometimes occurs, but clinical observation suggests that the usual distension—"bowed tendon"—is gradually pro duced by repeated limited laceration of the peri tendinous covering, and that later the body of the tendon becomes affected by extension from the peritendineum (paratendinitis).

Effects of Strain.Coleman taught that sprain is"an inflammation of the cellular tissue connecting the perforatus and perforans to gether"; and Percivall, while holding that tendons are incapable of extension and are too firm and strong to sustain hurt from common accident, recognized the fact that they are sur rounded by a soft, delicate tissue which must, every time they are forcibly pulled or stretched, be extremely liable to laceration. Since then— excepting those who, perhaps too seriously inter preting the words of the preacher,"he that increaseth knowledge, increaseth sorrow,"have been content with offering opinions—very few have taken the trouble to inquire into the nature of strain, and Fader, Veterinary-Major in the French Army, has done more than any other to explain the pathology of tendinitis.

Excessive tension of a tendon causes rupture with retraction of fasciculi, laceration of the peritendinous covering and interfascicular septa, extravasation, and sero-sanguineous exudation. The exudate fills the interfascicular spaces and distends the areolar septa, the hitherto quiescent tendon cells increase in size and become active, while the damaged fibres are partially converted into a structureless hyaline pulp. Inflam matory reaction is set up, and in the reparative process the breach in the tendon is made good by granulation tissue, which is formed by the agency of the tendon cells and the fibro blasts of the connective tissue adjacent to the lesion. Eventually the new-formed tissue under goes cicatricial contraction. Though tendinitis, caused by strain, is an aseptic process it nearly always produces permanent distension at the seat of injury. Resolution is a possible termina tion, but in most cases of sufficient intensity to attract attention, repair is imperfect, and after apparent recovery it is exceptional to find the tendon normal or quite free from adventitious growth. As a rule there remains a nodular or diffused thickening of the tendon or peritendin ous covering. A tendon once inflamed is pre disposed to relapse, and too frequently, owing to insufficient rest, to position, or to persistent irritation, the result is chronic tendinitis.

Post -mortem examination of a chronic or indurated strain of the subcarpal ligament shows, in addition to remarkable intrinsic dis tension of the ligament, considerable peripheral increase from new formation of connective tissue. The suspensory lying in front is not involved, but the borders of the subcarpal ligament are firmly united to the perforatus and its covering by the enormously thickened apo neurosis. This union forms a tube for the per forans, which remains free within the synovial sheath. At the point where the subcarpal joins this tendon, and below to a variable extent, the perforans is more or less distended, but above, within the carpal sheath, the tendon may be normal, atrophied, or hypertrophied according to the intensity and duration of the inflamma tion, and the degree of compression exerted by the surrounding new fibrous growth.

Partial atrophy of the perforans may result from chronic inflammation of either the sub carpal ligament or perforatus. Hypertrophy may be due to a compensatory cause, the per forans, owing to failure of the perforatus or one of the ligaments, being more actively engaged in supporting weight. But sometimes the increase in thickness is pathological and due to tendinitis either primary or arising by extension from the subcarpal ligament, per foratus, or aponeurosis. The metacarpal vessels and nerves running through the thick fibrous growth under stress of increasing compression may be injured, and in fact the wall of the meta carpal artery is much thickened, and the nerves, including the branch which crosses the per foratus, are expanded and flattened, but other wise they appear normal. Sclerosis, arteritis, and phlebitis of the vessels, and sclerosis and perifascicular exudation of the nerves, have been observed by Pader, and he suggests that possibly this interstitial neuritis may contribute to the lameness.

Similar peritendinons alterations with ulti mate ossification of the fibrous growth occur in connection with chronic tendinitis of the ' per forans at the fetlock, usually of the hind limb. The rupture occurs between the sesamoids and the os coronae, where the perforans is constricted and relatively weak. The tendon presents a diffused distension extending above the sesa moids and forming a notable prominence behind the pastern. The synovial sheath and apo neurosis, inflamed and thickened, appear more seriously affected than the tendon. Some observers, probably impressed by the more obvious lesion, maintain that synovitis pre cedes the tendinitis; but Siedamgrotzky, after numerous investigations, held that in every case of chronic inflammation of the sesamoid sheath accompanied by lameness and tumefaction, the perforans has been partially ruptured, and that the synovitis is the result of extension from the tendon. Post-mortem examination of a chronic case does not reveal the order of attack. Both tendons and the synovial sheath may be affected, the perforans by distension, the perforatus by peritendinous increase, and sometimes the apo neurosis shows more extensive alteration than either the tendons or synovial sheath. In the fore limb, at the perforatus ring, the perforans alone may be distended coincidently with inflam mation of the sesamoid sheath. In this case the synovitis appears to precede the tendinitis, which invades the sesamoid surface of the tendon. Inflammation of the synovial lining of the carpal sheath is usually associated with strain of the flexor tendons or check ligament.

There is often marked lameness with inability to flex the limb. A firm swelling appears at the upper part of the back of the knee-joint, usually at the inside, and a second enlargement below the knee, extending as far down as the middle of the cannon. The two are actually conVent, but appear to be divided, owing to the presence of firm fibrous bands which sup port the carpal sheath behind the knee. The condition is sometimes referred to as"knee thoroughpin." Tendinitis of the perforatus at the middle of the cannon usually arises from a very limited initial injury of the tendon or the peritendinous covering. At first the leg is merely filled or oedematous over a portion of the tendon, and the lameness, not very marked, disappears with the swelling under rest and bandaging. Gradually, however, the tendinitis extends, the swelling becomes firmer, and persists in spite of bandages and simple remedies. At this stage careful treatment may arrest the progress of the inflammation, but in most cases insufficiently rested the peritendinitis invades the aponeurosis, the borders of the perforatus become united to the subcarpal ligament, and permanent disten sion and adhesions extend far beyond the seat of primary injury.

In high strain and in strain at the fetlock, the distension of the perforatus is complicated by synovitis of the carpal or sesamoid sheath, which always aggravates the lameness and retards recovery.

Here mention may be made of those cases of"diffused thickening of the flexor tendons"of one or both fore or hind limbs. The leg from knee or hock to fetlock is enlarged over the tendons by persistent, firm, not very sensitive swelling, without abrasion or lameness, and causing no inconvenience beyond raising the heels slightly off the ground. In this condition the tendons are not really thickened, but the aponeurosis and peritendinous coverings form a dense fibrous shield which appears to inter fere very little with the movement of the flexors. What is the cause ? Wear and tear, constitu tional weakness, heredity, or what ? Though sometimes referred to rheumatism, the altera tion gradually produced is so painless in its progress and effects that one hesitates to accept this explanation. A more feasible answer may be found in the effects of excessive work, and probably the chronic peritendinous thickening arises from the stress of constant heavy traction in cart horses, and from jumping and prolonged galloping in hunters and other saddle horses.

In strain of the suspensory above its bifurca tion the distension at first is lax and compres sible, but as repair advances the injured part becomes harder. Its connective-tissue covering participates in the inflammatory process, but the peripheral increase is less extensive than in flexor strain. The recessed position of this portion of the ligament and its separation from the subcarpal and tendons by the aponeurosis and a connective tissue layer possibly explain the frequent escape of the tendons from in vasion. But in strain of one of its branches the consecutive inflammation not only distends the suspensory but extends through the medium of the aponeurosis to the perforatus and lateral sesamoid ligament and produces one-sided chronic enlargement of the fetlock.

Parasitic invasion of the suspensory and per foratus has been observed in Austria, Russia, and the South of France. The parasite (Filaria reticulata) in excavating galleries causes the formation of painless nodular enlargement of the ligament, which may be mistaken for old standing distension.

Filariasis of the suspensory has been investi gated in Russia by Tchulovski and in France by Pader, and a full description of the condition will be found in the Journal of Comparative Pathology for December 1908. In one district Pader examined, post-mortem, 43 horses, asses and mules, and found 35 affected in various degrees; and Tchulovski had 51 cases in 53 horses examined at Kazan. Apparently, while active, the parasites weaken the resistance of the suspensory and predispose it to strain or rupture. After a time the parasites perish and the lesions are repaired, but the ligament remains more or less enlarged. So far the writer has not been able to find a suspensory with the parasite. In a few foreign-bred ponies the ligament of one or both fore legs has been found nodulated as in filariasis, but the cause could not be ascertained. In this country owners are not readily persuaded to sacrifice useful animals to gratify surgical curiosity.

Symptoms and Diagnosis. The symptoms of strain being familiar, only a few will be referred to here. Diagnosis bristles with difficulties fully appreciated by the writer, who being him self unable to see clearly, can hardly show the way to others. Every strain is accompanied

by the usual signs of inflammation, and soon after the injury swelling, pain, and increased heat of the strained part are discoverable. These symptoms, as well as lameness, vary not only with the measure of the inflammation but to some extent with the position of the strain and the tendon or ligament involved. Lame ness is more marked in subcarpal or perforans strain than in strain of the suspensory or per foratus. Severe strain of the subcarpal or perforans appears to be much more painful than other strains of equal extent or intensity. The horse walks lame and may be unable to trot. In strain of the perforatus ("bowed tendon") or suspensory, walking may be free from nodding, and trotting may be comparatively easy. The difference in degree of the lameness exhibited in the two cases is due partly to func tion, and partly to synovitis, which is almost a constant accompaniment of perforans strain and only an occasional complication of strain of the perforatus. Excepting an inch or two at the mid-cannon and at its termination, the perforans tendon throughout is invested by synovial membrane, while the perforatus is only so covered in places. The horse's action may be suggestive, but in few cases does action alone warrant the diagnosis of strained tendon. Inspection of the lame leg, except in recent bowed tendon, may mislead, and a case some times occurs in which the exception should be disregarded to avoid error. Painful ce dem a over the tendons is helpful, but its many causes unconnected with strain should be considered. Manipulation of the injured region is most useful m forming an opinion of the nature of the case, and there is no better method of arriving at a differential diagnosis of the cord affected. In practice the advantage of distinguishing the strained from the unstrained tendon or ligament may not be very great; treatment varies very little, and often the diagnosis"strained tendon"is sufficient, and perhaps it is fortunate that the horse owner in this particular is not more exacting. Differential diagnosis of many cases is extremely difficult, and of some impossible, even after repeated examination of the leg. But bearing in mind that in most of the commoner strains the inflamed peritendinous tissues establish an intimate and more or less extensive connection between the tendons, a comprehensive view may be taken by anticipat ing probable extension of the tendinitis to parts which are neither distinctly normal nor yet clearly affected. In this way lies safety in diagnosis. The observer may be confident and fully justified in diagnosing strain of the sub carpal ligament, and at the same time quite unable positively to state whether or not the perforatus or perforans is also implicated, but his experience of similar cases should enable him to affirm that the perforatus will not escape.

In diagnosing strain just under the knee, the subcarpal, perforans, perforatus, carpal sheath, and the aponeurosis merit consideration.

Firm painful swelling near the cannon and extending four or five inches downwards usually denotes, in the cart horse, subcarpal strain, and in others, strain of the perforans with synovitis of the carpal sheath. Superficial swelling ex tending upwards and distending the carpal arch generally arises from perforatus strain, and when the tumefaction is one-sided and very painful, external injury may be the cause. Clipping the hair over the tendons facilitates further examination. By flexing the knee and tracing singly the ligament and tendons, a centre of tendinitis will be discovered. Later, in a week or two, the inflammation having extended, while a diagnosis of strain can be safely made, uncertainty remains as to the cord primarily or mainly affected. In strain of the subcarpal ligament at its junction with the perforans, the resulting distension appears to involve the tendon as well as the ligament, but post-mortem examination shows, at least in a few cases, that the lesion is restricted to the portion of ligament that is joined to the tendon. In young horses lame from high splint, cedema may extend to the adjoining aponeurosis and excite suspicion of flexor strain. Doubt will be satisfied by applying a bandage, which generally removes the swelling.

Strain of the perforatus at the middle of the cannon may develop insidiously, or it may be shown by immediate conspicuous engorgement over the tendon. The slowly progressive case at first may be overlooked, because there is very little interference with function, but the other at once attracts attention. The horse is very lame, and the swelling, quickly formed, may have to be reduced before the nature of - the injury can be ascertained. Usually the strain is severe and accompanied by acute tendinitis, which rapidly produces fusiform deformity of the tendon with extensive peritendinous thicken ing. The progressive case begins by the forma tion of a warm, slightly painful, compressible swelling over the tendon. This may be attri buted to a blow, but there is no abrasion; though the absence of signs of contusion on a leg bandaged at work should not altogether exclude external injury as a possible cause. If arising from strain the ce dema diminishes or disappears under bandages and re-forms when the leg is left uncovered. Lameness is hardly noticeable, and the horse may not be rested. In time, depending on the degree of injury and the horse's work or exercise, the swelling ex tends, becomes harder, and does not yield to lotions or bandaging. The tendon and its covering are inflamed, and short or elongated permanent distension will result. Owing to various causes the horse is kept going. Mean while peritendinitis extends, further laceration may occur, adhesions form, and eventually the condition of the leg and increasing lameness enforce rest and treatment.

Differential diagnosis of strain at the fetlock, fore or hind, is seldom easy. Occasionally, and only at the beginning, a case which appears to represent a flexor strain may be entirely due to synovitis of the sesamoid sheath, and as the perforans cannot long escape invasion, the cause of lameness may be puzzling. The condi tion of the inflamed synovial sheath hinders exploration of the tendons. Both flexors may convey the impression of distension, while only one is inflamed; and in the chronic case para tendinitis (aponeurosis and synovial sheath) pre vents intimate examination of the parts. Some times the position of the fetlock or the heels assists in the diagnosis of suspected flexor strain. Synovitis with knuckling, the foot resting flat on the ground, suggests perforans strain; synovitis with raised heels points to perforatus strain and paratendinitis or aponeurotic thicken ing; and synovitis with knuckling and raised heels to tendinitis of both flexors. Firm pain ful swelling over the flexors below the sesamoids usually arises from perforans strain, complicated by synovitis and paratendinitis, and much of the thickening or bulging behind the pastern proceeds from changes in the aponeurosis. In some cases there is distension of the inferior sesamoid ligaments.

Recent suspensory strain may be recognized very easily, but diagnosis of the chronic case of branch strain may be rendered very difficult owing to adventitious growth and adhesions. The affected ligament should be traced in the raised limb and compared with a healthy one. Distension caused by strain is rapidly formed and always more or less diffused. Lameness varies, and considering the condition of the ligament, it may be little marked. After rest and treatment functional recovery is the rule.

Prognosis of Strain. The discussion of pro gnosis, in the absence of the horse, is unlikely to be profitable, and this part of the subject will be passed with the remark that of the various strains, considered functionally and economically, subcarpal is the most serious. The others, placed in the order of diminishing importance, are perforans, perforatus, suspensory. This order should not be regarded as inflexible, but merely as the outcome of experience of average cases.

Treatment. Treatment of a recent case com prises rest, which too often is ridiculously short and inadequate, raising the heels, warm fomenta tions to mitigate pain, ease tension, and promote absorption; douching with cold water, hosing the leg, or applying lotions of ammonium chloride, magnesium sulphate, sodium chloride, zinc acetate, alum, or lead subacetate, to remove congestion, lower local temperature, modify the inflammation, and hasten absorption of the exudate. Ice poultices and continuous irriga tion with cold water have similar effects, while warm moist compresses renewed every half hour are strongly recommended by Moller, and dry uniform compression by means of cotton wool and bandages by Hunting. A thick layer of a mixture of hard and soft paraffin contain ing white lead or finely powdered Epsom salt applied to the strain and covered with cotton wool and a bandage is said to be beneficial. Evaporating lotions, anodyne liniments, and astringent pastes are also employed; but prob ably encasing the shank with cotton-wool held securely in position by an elastic or rubber bandage and keeping the horse as far as possible at rest will be found equally efficacious. The early treatment of an acute case continued for from four to ten days or longer lessens or removes the oedema, heat and pain, and isolates the firm, more or less extensive and still sensitive distension, which is now in process of repair. For some time the lesion remains apparently stationary, and though the preliminary remedies, supplemented by hand-rubbing or massage, may be continued, a cold-water bandage or a com press soaked in saturated solution of Epsom salt applied to the leg night and day, may be found sufficient to prepare the case for more active treatment.

Massage as a therapeutic measure in human and veterinary practice was introduced by Girard, veterinary surgeon to the Imperial Guard of France, in 1857, and its rational application to strained tendons has been ex plained by Waldteufel. He uses an antiseptic pomade composed of lard, 250 parts, cresyl, 10 parts, to which water, 100 parts, is gradually added and thoroughly mixed to form a cream. After smearing the swollen part with the pomade, massage proceeds by very gently rubbing, from below upwards, all round the strain to unload the vessels and to remove extravasation. Pro gressive pressure with the palm or the palmar surface of the thumb and fingers should then be applied to the strained or painful parts, and always in the direction of venous return. After rubbing for fifteen minutes or so the part becomes softer and less sensitive. Then the pressure should be stronger and the movements of the hand accelerated for a further fifteen minutes. Massage should be practised for half an hour once or twice daily according to the case, and in the intervals the leg should be bandaged. This treatment gives excellent results in cases associated with much cedema.

Stimulation or resolvent treatment is indi cated in the stationary period while repair is taking place, or in two or three weeks after the accident, but some practitioners, immediately after diagnosis, apply a mercurial all over the strained region. The favourite agent is oleate of mercury or diluted mercurial ointment.

Frohner recommends the treatment which he saw employed at the Imperial Stables, Vienna. After the usual preliminary applications to the strained part, the hair is clipped and the skin washed and disinfected, then biniodide of mercury ointment (1 to 4 or 5) is rubbed in thoroughly for fifteen minutes, and covered with absorbent cotton and an ordinary bandage, which are allowed to remain in position for two weeks. After twenty-four hours the bandage becomes moistened with exudate which soon dries. By resorting to this method the applica tion of the cautery to chronic cases may not be required.

Cagny, with a large racing practice, in the treatment of strain, in place of vesicants and sometimes firing, employs subcutaneous injec tion of a drachm of rectified oil of turpentine to which he adds a small proportion (1 in 50) of a 5 per cent alcoholic solution of guaiacol, to render it aseptic and to diminish the pain following the injection. This method produces much additional swelling and frequently abscess formation, which, however, is seldom serious. He claims that the results are as good as those obtained from vesicants or firing, the leg is not permanently blemished, and this remedy is more easily applied than the cautery, but he admits that some horses are much agitated for several hours after injection, a few refusing to feed for two or three days; that the cedema may be so enormous as to prevent all movement for a week, and that it is slow in disappearing.

For perforatus strain, Joly, of the Training School, Saumur, in 1901 introduced the treat ment by peritendinous insufflation of filtered air, followed by massage. The operation, carried out with due regard to antiseptic pre cautions, may be performed in the standing or recumbent position. A tourniquet is applied to the forearm. The air, drawn through iodo form gauze, is slowly injected by means of a Potain's aspirator furnished with a fine needle, which is pushed into the subcutaneous tissues over the distension on the posterior line of the leg. When the air has penetrated the healthy, oedematous or indurated tissues of the strained part, the needle is withdrawn and the puncture closed with collodion. Next day the insufflated region should be gently kneaded to drive the air, which tends to spread excentrically into the meshes of the inflamed tissues. Massage is repeated morning and evening at the most distended parts, and finally the leg is douched with cold water. By this method, Joly states that the effects of peritendinitis are rapidly and radically reduced, and that the indurated centre of tendinitis is quickly isolated and often reduced as well. In fifteen days, in certain cases, the tendon has become perfectly cool, clean, insensitive, and resistant to the effects of work. Insufflation is useless for old-standing extensive induration of tendons, but for cases passing into the chronic state repeated injec tions followed by massage or counter-irritation may bring about functional recovery.

Chronic strain cannot be cured, though usually an attempt is made by further treatment to render the horse workable. With owners and veterinarians cauterization is the favourite remedy, but perhaps it is less popular than formerly, and it cannot be described as a specific for strained tendons. Superficial firing, in lines or by budding, when useful at all is most success ful in simple cases, but of the many strained tendons fired in this manner the advantage to the horse has seldom been very marked. Deep line-firing probably is more beneficial than any other mode of cauterization, but whether it acts by inducing the formation of a more extensive subcutaneous cedema or by merely exciting cutaneous inflammation with consecutive com pression of the strained part, is not known.

Firing in points, the needle penetrating the induration, has a very limited application. Pyro-puncturing may be justified on the assump tion that it reproduces deep-seated inflammation and establishes a further process of repair and consolidation of the distension. But unfor tunately for the success of this method, it pro motes the formation of adhesions between the skin and subjacent tissues and shortening of the tendon, disadvantages that detract much from its value as a remedy for strain. Besides, deep puncture - firing is dangerous where a synovial sheath exists, and an operation that may produce open synovitis should not be undertaken without due consideration. For perforatus strain at the middle of the cannon and strain of the suspensory, puncture-firing is useful enough.

Neurectomy. When other treatment fails, neurectomy should be tried. Frequently it is too long delayed. It enables a horse that has become useless from chronic strain to work moderately for a year or longer according to the case. But like other treatment, neurec tomy has its limits of usefulness. It does not arrest the tendinitis, which after operation may become aggravated. It does not prevent, while it may hasten, shortening of the tendon, and in some cases it does not entirely remove the lameness, which is said to be mechanical. It is not advisable for saddle horses; and for heavy draught horses, while permitting profitable dis posal, it does not give satisfaction. Notwith standing these objections neurectomy should not be neglected in suitable cases of chronic strain.

Complete subcutaneous rupture of perforans, perforatus, or suspensory may be simple, in volving one cord; double; or multiple when both flexors and suspensory are ruptured; spontaneous or primary, when affecting a clean and apparently healthy tendon or suspensory; acquired or secondary, when following neurec tomy, tendinitis, synovitis, contusion, gathered nail or fracture.

The position varies; perforans, at the pastern, near its insertion, or at the sesamoids. Sub carpal ligament (?); perforatus, a few inches below the knee, at the fetlock, or towards its insertion. Suspensory, one or both branches near sesamoids. Upward splitting of body of ligament sometimes included with rupture.

Complications. Fracture (sesamoids, navi cular, suffraginis); synovitis, carpal sheath (perforatus and (?) subcarpal), sesamoid sheath (perforans, perforatus, suspensory); and navi cular bursa (perforans); rupture of fetlock joint capsule, extravasation.

Causes. Sudden violent hyperextension ex ceeding the limit of resistance of tendon or suspensory; prolonged galloping, with muscular fatigue; carrying too much weight; violent struggling when cast; excitement and pressure during service (both fore flexors in mare); jumping in hunters and chasers, fore leg (flexor or suspensory), hind leg (suspensory); synovitis of sesamoid sheath (perforans); tendinitis; neurectomy (perforans); gathered nail (per forans), navicular disease, etc.

Symptoms . These are very variable. In spontaneous rupture, sudden lameness or loss of power, horse unable to go on, limb advanced or held up, acute pain, horse very restless, sometimes kicking violently, and in kicking may luxate a hoof or more than one; rapid engorgement extending above and below the seat of rupture. Secondary rupture may be preceded by swelling of the pastern or leg, or it may take place without premonitory sign. In the stable the horse may be found with the fetlock lowered or the toe turned up, showing very little uneasiness. At exercise the horse may stumble or fall at the moment of rupture, when lameness and the deformity of the fetlock attract attention. If examined immediately after the accident, the ends of the rupture can be felt; but later, owing to swelling, diagnosis may be doubtful. When the leg is under weight, in perforans rupture the fetlock sinks and the toe turns up; in perforatus rupture the fetlock is knuckled or unaltered; and in suspensory rupture the fetlock descends and the foot rests flat on the ground. In double flexor rupture {suspensory intact) the fetlock descends and the toe turns up; and when the three cords are ruptured (complete breakdown) the fetlock and pastern rest on the ground. In rupture follow ing tendinitis with peritendinous adhesions, the fetlock at first may sink very little or not at all, but later it descends as the adhesions be come more and more stretched or lacerated. Occasionally after a severe gallop or jumping trial a fore fetlock sinks and swells posteriorly as if caused by rupture of tendon or ligament. On post-mortem examination both flexors and suspensory are found intact and the only dis coverable lesion is a thickened aponeurosis. What is the explanation ? Is the sinking of the fetlock due to elongation of the flexor muscles, or to rupture of the aponeurosis which supports the fetlock ? Prognosis. The discussion of the prognosis of complete rupture, like that of partial rupture, to be useful, requires the presence of the patient. Generally, however, the prognosis is favourable in single, uncomplicated primary rupture of suspensory or perforatus, and less favourable but not hopeless in bilateral rupture of either cord. It is exceedingly doubtful in perforans rupture, and in cases following neurectomy or gathered nail slaughter is imperative. Rupture complicated by sesamoid or other fracture, while not always incurable, is usually sufficiently serious to suggest slaughter. Sometimes the value, sentimental or exhibition, or the breeding of the animal, if entire or a mare, prevents immediate slaughter of an apparently hopeless case, which eventually makes a useful recovery. Uncomplicated cases of single or double spon taneous rupture should not be too hastily con demned so long as the owner is willing to risk the cost of prolonged keep and treatment.

Treatment. Rest need not be emphasized, but the length of rest required should be made clear to the owner; if the case is promising and the horse is to resume fast work he should have a.year. Less may be sufficient, but more may be advantageous. A long rest furnishes the best means of ensuring success or of escap ing failure in the treatment of injured tendons. In most cases slings are useful, if only for a week or two, and when the fetlock is much lowered a surgical shoe should be employed. Anodyne, refrigerant and astringent lotions or compresses to diminish the pain and swelling, then plaster or starch bandages to assist in sup porting the fetlock, and after an interval, bandages having been discontinued, the leg may be blistered or fired. J. M.

Knuckling at the Fetlock. This condition may occur at any age and is usually the result of disorders existing in other parts of the limb. Occasionally foals are born with well-marked knuckling at the fetlock-joint. This occurs more often among thoroughbreds.

Causes. In foals the actual cause is a matter of dispute. Probably congenital contraction of the flexor tendons is often responsible, or ad hesions of the tendon and overlying tissues may occur as the result of the fetlock being main tained in a position of flexion whilst in the uterus.

Some have suggested a lack of proportion between the framework and the tendinous por tions of the limb; in other words, excessive length of the metacarpus or metatarsus without proportionate elongation of the flexor tendons. Myositis of the flexors has also been blamed.

In older horses contraction of the flexor tendons, subearpal ligament or suspensory liga ment may be the cause, and in the majority of cases of knuckling one of these will be found responsible.

Ringbone and chronic foot lameness may also produce an upright or knuckled condition of the fetlock, probably because the position affords the animal some relief from pain. Occasionally bony growths at the back of the pastern mechani cally shorten the tendons.

Overgrown heels and upright feet will give rise to moderate knuckling, which becomes chronic through shortening of the relaxed flexor tendons. The same result may follow lame ness in any portion of the limb associated with prolonged flexion of the fetlock, notably long standing foot lameness, radial paralysis, and lameness arising from fracture of the deltoid tubercle of the humerus, which is frequently followed by contraction of the tendons. These, however, may again become normal with work or exercise.

Sesamoiditis and distension of the superior sesamoid sheath and hydrarthrosis of large size may be responsible.

Symptoms. Three degrees of knuckling are usually recognized.

(1) When the foot, coronet, and fetlock are upright"—that is to say, vertically placed or in a line at right angles to the ground.

(2) When the fetlock joint forms an angle open at the back of the joint.

(3) When the front of the fetlock lies beyond a vertical line drawn at right angles to the ground from the toe of the foot.

The degree of knuckling may vary according to the tissues involved. Hence contraction of the perforans tendon may produce marked volar flexion of the whole of the limb from the fetlock downwards, so that the heel of the foot is raised from the ground and the horse stands and walks upon the toe. Contraction of the subcarpal ligament, the result of repeated strain, often involves a portion of the perforans tendon and produces knuckling, but frequently thickening of the ligament alone exerts sufficient pull upon the tendon to cause a marked straightening of the phalangeal articulations.

Contractions of the perforatus and suspensory ligament produce knuckling of the first and second degrees, the foot being firmly planted upon the ground, the animal being able to bear his weight on heel and toe alike.

The condition per se is not a painful one unless either of the metacarpal or plantar nerves be involved in the fibrous thickening, which during contraction may exert pressure upon the sensi tive fibres. This is not a common complication, and is more likely to occur after line-firing or blistering, which produces subcutaneous inflam mation, which may, and probably always does, extend to the deeper tissues. Subsequent con traction of the organised inflammatory products may then cause pressure changes in the nerve.

Knuckling may, however, be attended by pain in the limb when it arises from acute strain of the tendons with a great deal of thickening in the early stages.

The degree of lameness in chronic cases varies according to whether the knuckling be excessive or slight. In the latter case (upright joints) there may be little interference with action, beyond a tendency to stumble. When more pronounced, the limb bears very little weight whilst the animal is at rest, but during move ment the foot is placed upon the ground with confidence, excepting in perforans contraction, when the animal"goes on the toe,"being in many cases unable to lower the heel sufficiently to reach the ground. There is, however, a peculiar hesitation displayed in the gait, with a tendency to stumble. The horse quickly tires, and when knuckled in both fetlocks may be useless for work and only able to remain stand ing for a limited period. The lameness usually arises from the condition of the tendons, which are unable to play their part in sustaining weight and maintaining balance. Possibly the altered relations of the joint surfaces contribute to the uncertain, insecure gait, but as the articular surfaces themselves show no lesions, the lame ness must be considered as mechanical excepting when acute tendinitis or ostitis is coexistent.

Prognosis. This depends upon the age of the animal, the extent of the knuckling, and struc tures involved.

Foals born with"overshot"fetlocks usually recover hi the course of a few weeks or months. In the majority of cases the shorter period suffices, there being no changes in the tendons.

Sometimes knuckling of the third degree is seen. The foal may then walk on the front of the fetlock and produce serious injuries, which may necessitate slaughter.

Recovery usually depends upon whether the animal can stand upon the foot itself. In cases when this is possible, time alone usually brings about cure.

In two -year - olds, especially among racing stock, knuckling may occur in colts or fillies which were sound at birth, and prognosis is then very uncertain. Some cases recover completely, but these are rare; others partially recover but are rendered useless for racing, whilst some develop into permanent cripples. The condi tion is frequently bilateral.

Knuckling, occurring as the result of strained and contracted tendons in older horses, is always a serious condition and when well marked can only be benefited by operation, and even then the results are not always satisfactory. In cart horses the prognosis is more favourable than in lighter animals. Even a moderate degree of knuckling in a hack or hunter renders it unsafe.

Treatment. This must vary somewhat accord ing to the cause of the knuckling. When it has occurred as the result of resting the limb or prolonged flexion of the phalanges, as may happen in cases of chronic foot lameness, radial paralysis, etc., elongation of the tendons will usually occur after the primary lameness has ceased and when the limb has again been brought into full use. The process of recovery may be aided and hastened by the use of a suitable shoe. In knuckling of the first and second degrees a thick toe with tapering heels will be sufficient, but in extreme cases it may be necessary to weld a toe-piece or prong on to the shoe to prevent the toe of the foot from being carried behind the line of support. By this means the animal is forced to place weight upon the foot and so to exert a pull upon the tendons.

Whilst in the majority of cases of knuckling due to inaction of the flexor tendons, recovery occurs sooner or later, the same cannot be said of knuckling arising as the result of inflamma tory changes and contraction. Such cases do not readily respond to treatment, and the best we can do in most instances is to bring about some amelioration of the symptoms.

Knuckling of the first and second degrees may sometimes be improved by line-firing and blis tering, and at the same time surgical shoes such as those described above may be of assistance. Care must be exercised in shoeing so that fresh strain and a recurrence of inflammatory symptoms may not result. Attempts to secure stretching of contracted tendons should only be made when the condition is of some standing and not associated with pain.

In any case a prolonged run at pasture is a necessary accompaniment of any attempt at treatment.

Tenotomy, much practised in the past, has now to some extent been discarded, mainly on account of the troublesome complications which may ensue and because in many cases the last state was worse than the first. In horses which are worth treatment, will repay prolonged idle ness and cannot be otherwise rendered useful, tenotomy, properly performed, will in many cases effect a cure or at least restore the animal's usefulness, especially for slow draught work.

It is important to recognize the exact seat of the contraction. This is often difficult or im possible, owing to the amount of fibrous thicken ing present. The position of the foot and fetlock joint will afford some additional evidence, but as in many cases there is fibrous adhesion between the two tendons and often between the edges of the check ligament and the perforatus as well, which thus form a tube through which the perforans tendon glides, it may be necessary to sever both tendons. When these adhesions between the tendons cannot be broken down by means of the spatula the operation usually ends in failure. In any case the perforans should first be divided and forced extension applied to the limb with the object of breaking down any loose adhesions between the tendon and aponeurosis, which may prevent extension of the phalanges. Should this be still impossible nothing remains but section of the perforatus tendon also. Knuckling of the first degree may still remain from thickening and shortening of the suspensory ligament.

When the perforatus has been divided, excess ive dorsal flexion may occur and prevent the horse from using the limb. It is, however, essential that a certain degree of dorsal flexion should be present, this indicating complete division and separation of the tendons.

The next step in treatment, and the one which decides whether the operation shall be a failure or success, is the application of a surgical shoe. If dorsal flexion be too great the heel may be raised somewhat; if insufficient, the toe must be thickened and the heels lowered. As the cicatricial tissue commences to contract, the heels must be kept sufficiently low to maintain a degree of dorsal flexion considerably in excess of the normal position, otherwise the termina tion will be unsatisfactory and knuckling will again ensue. Exercise is essential during the early stages of treatment excepting after section of both tendons simultaneously, when it may be found necessary to place the horse in slings and hold the limb in the position of normal phalan geal extension, by means of a splint, for the first week. After this, exercise in a loose-box for another week may be necessary before turning the animal away to pasture.

Foals usually recover with exercise alone provided they can stand, but two-year-olds are very resistant to treatment. In both cases forced extension should be practised daily when the patient will permit of it, the leg being held up and backwards by an assistant whilst the operator forcibly attempts to extend the fetlock by downward pressure on the heel of the foot. Hand-rubbing the tendons may also assist.

Various forms of extension apparatus are on the market, and Friebel's type is recommended. Two-year-olds should be shod with thin heels, thick toes, and a toe-prong when it is thought necessary.

Distension of the bursae of the extensor pedis and extensor suffraginis tendons may occur at the front of the fetlock in a fore limb. In the hind limb the bursa of the extensor pedis tendon may be similarly affected. The cause is usually external violence, sometimes brought about by striking the part against the manger supports, or against a wall or door, or through sudden knuckling. Falls may also cause bruising of the front of the fetlock, and, when the skin is broken, dangerous complications occasionally ensue, as the bursa of the extensor pedis is in some cases continuous with the synovial capsule of the joint.

Horses which sleep standing and which do not lie down, frequently injure this part from knuckling forward upon the fetlocks by night.

Prevention consists in removing any object against which the joint may be accidentally struck, and causing the horse to wear a leather boot or a Yorkshire boot for protection during the night, or altogether whilst in the stable.

In the early stages cold irrigation should be followed by the application of lead and alum lotion, or"white"lotion poured over a pad of cotton-wool, which should be retained in position by means of a bandage. Subsequently blister mg may help to reduce the enlargement.

Surgical interference should be avoided, owing to the risk of communication between the bursa and the joint capsule.

Synovial Distensions in the Fetlock Region."Windgalls."Inflammation and Distension of the Sesamoid Sheath of the Flexor Tendons. The great sesamoid sheath extends from the level of the"buttons"to the middle of the os corona, where it is separated from the navi cular bursa by an attachment of the perforans. It lines the aponeurosis and sesamoid pulley and is reflected on the flexor tendons, being modified at the sesamoids by the absence of endothelium on the anterior surface of the perforans. There is no synovial covering on a portion of the posterior surface of the perforatus, which is united to the aponeurosis of the fetlock.

The navicular bursa or sheath extends from the middle of the os corona to below the navicular bone; it forms a short synovial sac between the perforans and the navicular bone and its inter osseous ligament.

Distension of the sesamoid sheath may arise from inflammatory changes or may be merely a dropsical condition of the synovial cavity. The so-called"windgalls"are the result of an increased secretion of synovia which causes a bulging of the sheath upon either side of the flexor tendons. Windgalls may also be due to similar distension of the synovial cavity of the fetlock-joint. They then appear between the metacarpus and suspensory ligament. This type is often spoken of as"articular windgall,"whilst distension of the sesamoid sheath is referred to as"tendinous windgall."The latter condition is more often seen in the hind limbs than in the fore, and although it may appear in young horses it is more frequently seen in older animals which have been worked hard. It is very common in cart horses, but occurs almost as frequently in lighter horses which are accustomed to starting and pulling comparatively heavy loads, and especially in those used for trotting. Light vanners and cab horses are particularly susceptible; carriage horses and hacks are less frequently affected.

Whilst articular windgall is usually non inflammatory and often the result of weak con formation, tendinous windgall, although it may be congenital, is more frequently produced by persistent irritation of the sesamoid sheath, asso ciated with frequent slight or severe straining of the flexor tendons or suspensory ligament.

It is usual for the tendons, at any rate in the late stages of the condition, to become con siderably thickened and callous. The synovial sheath also becomes involved and its contents become fibrinous, the whole forming a hard, incompressible mass through which one can distinguish the component anatomical parts only with great difficulty.

The condition may also be associated with sesamoiditis, with changes between the gliding surfaces at the back of the bones and the flexor tendons, and in advanced cases there may be adhesion between these parts.

When inflammation of the sesamoid sheath occurs in hunters it is frequently the sequel to rupture or severe strain of the suspensory liga ment or of one of its branches.

Rheumatic bursitis may also affect the sesa moid sheath.

Symptoms. — Articular windgalls being the result of an excessive secretion of synovia into the fetlock-joint, have certain fixed anatomical relations. The synovial membrane is bounded in front by the capsular ligament and at the side by the lateral ligaments. Distension of the sac can therefore only make its appearance on the posterior aspect of the joint between the metacarpus or metatarsus and the suspensory ligament, or below the sesamoids between the suffraginis and the middle inferior sesamoid ligament.

They usually appear as small, firm but elastic swellings between the branches of the suspensory ligament and the metatarsus or metacarpus.

In their early stages the swellings are firm and tense whilst weight is placed upon the foot, but are easily compressible or may entirely dis appear when the foot is lifted from the ground.

When the pressure of synovia within the articulation is excessive, the lower synovial pockets between the sesamoid ligaments also become distended.

Whilst most windgalls are capable of com pression, yet with age and hard work they may become hard and indurated through thickening of their walls and the formation of masses of fibrin within their cavities. Knuckling may thus be brought about.

Lameness is seldom present excepting when the distension is sufficient to produce mechanical interference with the function of the joint.

Distensions of the sesamoid sheath (tendinous windgall) first appear as elongated compressible swellings running from the sesamoid bones as high up as the buttons of the splint bones, parallel with the edges of the perforans tendon.

With increase in the pressure within the sheath, distensions may appear below the sesa maids in the form of small oval swellings reach ing to the os corona and protruding at those points where the enveloping fascia is less dense.

Distensions of the sesamoid sheath may be compressible during their early stages and when they occur in young horses which have done but little or no work, but when associated with lame ness they usually take the form of constant fixed swellings which cannot be caused to dis appear at any position of the limb. The tend ency is for the swelling to increase in size and to become, under the influence of advancing age and work, complicated by inflammatory changes in the tendons and suspensory ligament with resulting thickening of the walls of the sesa mold sheath. The swelling eventually becomes so tense and indurated that the anatomical relations of the parts can only be made out with difficulty.

Lameness, though absent in most cases of pure tendinous windgall, is almost constant in teno vaginitis. The horse appears to take a shorter stride with the lame leg and throws his weight upon the toe. In severe cases the heel of the shoe is never brought to the ground. Lameness diminishes with rest but reappears with work. It is most marked whilst travelling uphill.

Treatment. Windgalls, whether articular or tendinous, may be benefited, at least temporarily, by bandaging. Articular windgalls seldom call for treatment, being usually merely eyesores. When, however, they are of sufficient size to produce mechanical interference with the action of the fetlock joint or when they become indur ated, line-firing and blistering give the best results. Cases have been reported of successful results obtained by removing an elliptical piece of skin from over the swelling and suturing. Could asepsis be guaranteed both at the time of and subsequent to the operation, this would appear an ideal method of removing the enlarge ment, but unfortunately in everyday veterinary practice conditions are seldom favourable, and the results may be far from satisfactory. Aspiration and injection of iodine solution followed by its withdrawal, with subsequent bandaging, may be tried but is often unsuccess ful, as the sac usually rapidly refills. The same remarks apply to the treatment of tendinous windgall.

When lameness occurs there is usually ten dinitis or sesamoiditis present as a complica tion.

In mild cases relief from lameness may be obtained by shoeing with heels, though this pre disposes to shortening of the tendon with chronic lameness as a sequel.

Nothing has yet been discovered which gives better results than the actual cautery. Line firing is best, and should be followed by the application of a mixed cantharides and biniodide of mercury blister. A long rest is required, and the animal may be with advantage turned out in a fiat field. Unfortunately cases which make an apparent improvement under treatment often again become lame when put to work.

Inflammation of the Bursa of the Middle Gluteal Muscle.The middle gluteus has three insertions, one into the summit of the great trochanter of the femur, another into the back of the trochanteric ridge, and a third which plays over the convexity of the great trochanter, being separated from it by a synovial bursa, and is inserted into the trochanterie crest. Strain of this latter tendon, or external violence, may produce distension of and inflammatory changes in the underlying bursa. Falling, struggling on the ground, and blows sustained in narrow doorways or gateways may be the cause of the injury.

Symptoms. The lameness usually appears suddenly and in most respects resembles hip joint lameness. The limb is abducted and the horse is inclined to travel"on the toe."Whilst trotting, the limb is advanced with an upward jerk of the quarter, with as little movement of the hip as possible. There is usually swelling of the trochanteric region.

Lameness may persist for some considerable time, or it may subside in a few days upon dis appearance of the swelling.

Treatment. Hot fomentations, followed by gentle massage and the application of a mild liniment such as Lin. camph. co., preferably with the addition of belladonna, may bring about recovery in mild cases.

Some practitioners recommend cold irriga tion, preferably applied with some force, as with a hose-pipe from a short distance, others advo cate alternate hot and cold packs.

Chronic cases may be blistered. Should this fail to bring about recovery, setons may be tried or the part may be fired in lines or points.

A high-heeled shoe frequently gives relief in long-standing cases. Rest is at all times the main factor in securing a favourable termina tion.

Bursitis Prwpatellaris — Capped Stifle.The prepatellar bursa sometimes becomes distended as the result of bruising. It then produces an enlargement, sometimes of the size of a coco nut, on the front of the stifle. The swelling is subcutaneous and its limits can be defined upon palpation, whereas in distension of the joint capsule the swelling lies deeper and cannot be displaced, nor is it so sharply defined. Lame ness is absent unless the enlargement is sufficient to interfere with movement. Inflammatory symptoms are rare.

Treatment. In the early stages cold fomenta tions, followed by lead and alum lotion, may considerably reduce the size of the swelling. Usually a small enlargement remains, and this may sometimes be caused to disappear by blis tering.

Should this fail, aspiration and injection of a 1 per cent solution of hydrarg. perchlorid. may be useful. The injection should be withdrawn after a few minutes. The operation may need repeating several times.

Surgical interference has occasionally been recommended. The bursa may be opened throughout its length and plugged with some agent which will destroy its lining. A 10 per cent solution of nitrate of silver on cotton-wool may effect this, but whatever agent be employed, the dressing should be carried out by the veter inary surgeon himself. A mixture of acid. carbol. liq. 1 part and glycerine 3 parts is a useful application for the purpose of arresting secretion.

Capped Hock. The

term"capped hock"denotes a swelling on the point of the hock. The nature of the condition varies according to the structures involved, and before proceeding farther it is well to consider the anatomical relations of the parts.

Underlying the skin is the bursa calcanea, a comparatively small mucous bursa resembling that occurring at the point of the elbow. Below this is the perforatus tendon, which forms a cap covering the tuber calcis, to which it gives off a slip of insertion on either side before pro ceeding farther down the leg. Completely covered by this fibrous cap is the insertion of the gastrocnemius tendon.

Lying between the gastrocnemius and per foratus tendon and covering a portion of the summit of the os calcis is the sheath of the perforatus tendon. This extends for from three to four inches above the point of the hock and for two inches below it, but for a short distance above the summit of the calcis it is supported by a strong fibrous band on either side, hence when this sheath is distended two distinct enlargements are visible, separated by the above mentioned band. The connection between the two is, however, quite evident upon palpation.

Capped hock may therefore be a superficial condition involving the skin and subcutaneous bursa or it may be a bursitis of the perforatus sheath. From extensive injury or the result of infection the lesions may involve both the cap of the .perforatus tendon and the tuber calcis itself.

Superficial capped hock is by far the more common condition and may be regarded as a hygroma resulting from bruising. The causes are usually self-inflicted injuries from kicking whilst in harness or in the stable, or occasionally from lying upon hard, stony floors. The position in which the animal lies sometimes has some influence in inducing bruising. Horses on rail are very liable to injure the points of the hocks, unless efficiently protected by leather caps or by padding the woodwork immediately behind them.

The symptoms of hygroma are swelling and, in the early stages, lameness, though this is by no means constant. The contents are at first fluid, but when the condition has become chronic there is usually considerable thickening of the skin with but a small amount of fibrinous fluid present.

In

synovial capped hock involving the sheath of the perforatus tendon there is usually severe lameness, especially if infection occurs, and in addition to enlargement of the superficial bursa the whole of the cap of the hock is swollen and cellulitis may extend for some distance above and below the tarsus. Well-marked distension of the perforatus sheath may be visible above and below the point of the hock on either side of the tendon. Necrosis of the tuber calcis may occur in rare instances: enlargement is not uncommon.

Prognosis. Superficial capped hock, though seldom a serious condition or liable to interfere to any extent with the usefulness of the animal, is nevertheless very difficult to get rid of and is seldom completely curable.

Some animals have a habit of striking the hocks and so constantly aggravate the condition.

Synovial capped hock is at all times a grave condition and requires a very guarded pro gnosis.

Treatment. In all cases of capped hock cold fomentations should be employed during the inflammatory stage. A mild astringent lotion such as of lead and alum may be used to supple ment this treatment.

As soon as the inflammation has subsided a biniodide of mercury blister may be applied, or the part may be rubbed with oleate of mercury, or painted daily with iodine or a lotion contain ing hydrarg. biniodid. grs. v., pot. iodid. grs. x. to the ounce of water.

Puncture has frequently been advocated, but it is seldom attended with marked success, as the bursa rapidly refills, and should infection occur the condition is rendered worse than before. To avoid refilling bandaging is necessary, and this is attended by so much resistance on the part of the animal as to render it impracticable.

The bursa may sometimes be ruptured sub cutaneously by applying a tight bandage whilst the opposite hind limb is held up. On releasing the animal his struggles to free the hock may cause the walls of the bursa to break and the contents may be discharged into the tissues and absorbed.

Radical operation—i.e. excision of the walls of the bursa after removing an elliptical piece of skin—is not to be recommended in everyday practice. In old cases with much fibrous thickening a charge may be applied to the cap of the hock and left in position as long as it will remain and then renewed. After several months a very considerable reduction may be evident.

Thiosinamine solution in one of the pro prietary forms may help to remove fibrous thickening.

Prophylaxis is equally important, and it is essential that the cause be discovered and removed. Usually some projection in the stable is responsible.

Synovial capped elbow must be treated on similar lines during the inflammatory stages, but when distensions remain which interfere with movement of the limb the best results will be obtained by line-firing and blistering.

Luxation of the Perforatus Tendon. The cap of the perforatus tendon is retained in position on the point of the os calcis by two lateral slips inserted into the bone. Occasionally, when a horse which has been confined to the stable is taken out for exercise and lashes out violently, one or rarely both of these lateral attachments may be ruptured, thus allowing the perforatus tendon to become displaced from its normal position and to slip to one side of the os calcis.

Similar injury may result from falls, especially whilst jumping, or from external injury, as from a kick by another horse.

The luxation may be either internal or external according to which insertion is ruptured. Internal displacement is the more common owing to the direction in which the tendon passes over the hock, i.e. from within outwards. In internal displacement the tendon remains fixed about half-way down the astragalus, or it may slip down its whole length. In external displacement it becomes arrested on the ridge of the bone. The latter is the more favourable condition.

Symptoms. In internal displacement the leg is raised but very slightly during progression. In both cases flexion of the hock is interfered with and a peculiar backward lifting movement of the leg may be noticed. The perforatus tendon can be seen to roll on and off its normal seat during movement of the limb.

Lameness is usually mainly mechanical unless the condition be complicated by injury to the tendon, bone, or tendon sheath.

Prognosis. Absolute recovery is doubtful in all cases as the limb cannot usually, in large animals, be kept sufficiently still for reunion of the torn slip to occur.

In outward luxation the tendon may become accommodated to its new position and the animal may again become workable. Harness horses may even be able to do fast work without apparent disability.

Inward luxation requires surgical treatment. The animal is cast and anaesthetized. A tape suture is then inserted through the perforatus tendon and through the tendo Achillis, whilst a second is inserted through the perforatus and the calcaneo-metatarsal ligament. The ends should be left hanging and tied after the horse is on his feet and in slings. Tape is preferable to wire as it causes more irritation, and the subsequent swelling and formation of connective tissue assists in maintaining the tendon in position.

Silver - wire sutures passed through the os calcis may be successful in some cases.

Distensions of Synovial Sheaths in the Tarsal Region—Distension of the Sheath of the Per f orans Tendon — Thoroughpin. - Thoroughpin is a distension of the sheath of the perforans tendon as it passes through the tarsal arch.

"Articular thoroughpin"is a term sometimes used to describe bulging of the capsule of the true hock-joint occurring at the hollow of the hock, that is to say, at the angle formed by the lower end of the tibia and the os calcis. At the same time, another distension may be present on the outer aspect of the joint in a similar position. Articular thoroughpin is usually associated with bog - spavin. True tendinous thoroughpin is characterized by the presence of a synovial enlargement on either side of the hock well in front of the tendo Achillis and on a level with the tuber calcis in the case of a thoroughpin of moderate size, or covering a large part of the inner surface of the hock in one of large size.

Stallions are very frequently affected with thoroughpin, but the condition is to be met with in all classes of horse, especially cart horses which have to start heavy loads. It is also prevalent in the upright hock with a short and poorly developed os calcis. This conforma tion is probably hereditary and may account for the fact that thoroughpin is often transmitted.

A thoroughpin is not always constant in size; it may appear suddenly and disappear without treatment, or it may vary in size according to the amount of work performed and climatic conditions. Thoroughpins are usually smaller in winter than in summer; with rest they de crease in size, but they rapidly assume their former proportions upon resuming work.

Lameness is very rarely observed excepting in the early stages of thoroughpin arising from sprain, as in starting a heavy load, jumping, rearing, or falling back upon the haunches.

Treatment is seldom required except in animals used for exhibition purposes. Firing is prob ably the best treatment for thoroughpin asso ciated with lameness, but in ordinary chronic cases it only substitutes one blemish for another. In exhibition animals Dean's operation—i.e. withdrawal of the contents by aspiration and injection of an antiseptic—may effect a cure. 1 per cent iodine solution with pot. iodid. or per cent alcoholic solution of hydrarg. per chlorid. with the addition of decolorized iodine may be employed, the liquid being subsequently withdrawn and the parts surrounded by a pres sure bandage.

Simple blistering does good in some cases.

Trusses are not so commonly employed now as at one time. They are hard to keep in posi tion, and better results are obtained by using an elastic stocking padded over the position of the distension. In either case the enlargement usually reappears when the use of the appliance is discontinued.

In working horses suffering from large thoroughpins some benefit will be derived from shoeing with calkins.

Distension of the Tendon Sheath of the Peroneus.The peroneus tendon in its passage over the outer aspect of the hock is provided with a synovial sheath. Either from traumatic injury, as striking against a bale, or from strain, this may become distended and then appear as a swelling at the upper end of the cannon bone. It varies in size from that of a walnut to that of a man's fist.

Lameness is exceptional.

Treatment is seldom required, but when de manded aspiration and subsequent bandaging may give good results, particularly as the part is suitable for the application of pressure dressings. Line-firing and blistering may also partly reduce the swelling.

Distension of the sheath of the extensor pedis is uncommon.

Distension of the sheath of the flexor pedis perforatus has been mentioned under the head ing"Capped Hock." The bursa lies between the perforatus and gastrocnemius tendons and between the former and the tuber calcis. The distension extends for four inches above the point of the hock, and a second distension usually appears about two inches below this, the two being continuous but divided into two parts by a transverse fibrous band.

The enlargement appears on both sides of the tendo Achillis and results from strain or over work, whilst faulty conformation plays a part. Lameness is seldom present excepting when the condition results from traumatic injury, as when associated with capped hock.

Firing in lines and the application of a blister will usually be sufficient when treatment is required.

tendon, strain, ligament, perforatus and fetlock